Field of the Invention
The present invention relates to a spindle-bearing protecting device and a machine tool equipped with the same.
Related Art
Conventionally, in the case of the spindle of a machine tool or electric motor failing, the cause of the failure is often wear or damage to the bearing. When performing machining using a machine tool or electric motor in a state in which the spindle failed, the precision of the work declines to become inferior. In addition, a great amount of downtime is generated by the time consumed in the restoration of the spindle, and thus the operating ratio of the machine tool declines.
Therefore, technology has been disclosed that, after measuring the deterioration in vibration of the spindle, and detecting a temperature rise, adjusts the amount of lubricant supplied to the bearing in response to the magnitude of the vibration and temperature rise, and prevents the main bearing from being scorched (for example, refer to Patent Documents 1 to 3). In addition, technology has also been disclosed that circulates a cooling medium inside an electric motor by way of a rotor blade (for example, refer to Patent Document 4).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2008-045681
Patent Document 2: Japanese Unexamined Patent Application, Publication No. S55-52927
Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2013-050193
Patent Document 4: Japanese Unexamined Patent Application, Publication No. H09-163683
However, a special structure has been necessary in the bearing in order to supply coolant or lubricant into the bearing efficiently. A bearing having such a special structure has not been able to share components with a spindle that does not have a life-extending function and components, while at the same time incurring extra cost.
In addition, it has not been possible to use a contactless sealed grease lubricated bearing with high maintainability at low cost. This is because, when trying to supply coolant or lubricant from outside to a normal contactless sealed bearing, the gap between the bearing seal and the bearing is small, and thus requires high pressure. In such as case, even if supplying coolant or lubricant using high pressure, a part of the coolant or lubricant will be repelled by the bearing seal, and the coolant or lubricant not reaching inside the bearing will adhere to the machine tool, electrical components of the electric motor, etc., and thus there is concern over conversely shortening the lifespan of the spindle.
In addition, with a contact-type seal such as an oil seal, since the spindle of the machine tool achieves high-speed rotation, it has not been possible to suppress discharge prevention of the coolant or lubricant.